We have a hook into XCloseDisplay now,
In addition to cleaning up the _cairo_xlib_screen_list this function also
needs to cleanup anything else that still refers to the same Display*.
Specifically, any Xlib-specific glyph caches will need to be cleaned up.
(I'm being intentionally vague about what/where those caches are as they
are undergoing a big rewrite at the moment.)
Fixed in 96d8f58daf279238d3a1dfcd4ed3710014e2aeea